Constant Net Implement Pump Valve Flow

ABSTRACT

A control system for a machine having a cylinder and an accessory is disclosed. The control system may include a pump configured to provide fluid to the cylinder and the accessory, and a controller operatively connected to the pump. The controller may be configured to operate the pump to provide a primary flow to the cylinder at up to a predetermined maximum level for the cylinder. The predetermined maximum level for the cylinder may be less than a maximum flow capability of the pump. The controller may also be configured to operate the pump to provide a secondary flow to the accessory utilizing a remaining fluid.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to machines and, more particularly, to a control system for a hydraulic system of a machine.

BACKGROUND OF THE DISCLOSURE

Machines, such as earthmoving and construction machines, generally include an engine that powers some type of hydraulic system. The hydraulic system may provide functionality and control to various aspects of the machines. For example, some work machines employ a hydraulic system for propelling the machine or providing hydraulic power to linkages of the machine. The hydraulic system may typically include one or more pumps used to convert mechanical power from the engine into hydraulic power.

Furthermore, the engine may be cooled by a cooling fan. Typically, the cooling fan can be belt driven off of the engine or hydraulically driven by a separate pump solely dedicated to the cooling fan. However, such configurations require additional hardware, which increases the costs of manufacturing and maintenance of the machine. In some machines, a main pump may provide flow to both the linkages and the cooling fan. However, an amount of flow required by the cooling fan may affect an amount of flow delivered to hydraulic cylinders associated with the linkages.

More specifically, the amount of flow used to spin the cooling fan varies depending on the fluctuating cooling requirements of the machine and a corresponding desired fan speed. This variability in the amount of flow to the cooling fan may cause a different amount of available flow to the linkages, thereby producing inconsistent cylinder velocities for a same operator joystick command. As such, the operator may experience inconsistent and unpredictable amounts of power when operating the linkages due to the main pump compensating for the variable cooling fan requirements. Accordingly, there is a need for a hydraulic system design that provides expected flow requirements to the linkages and a consistent joystick to cylinder velocity relationship without adding extra hardware for the cooling fan.

A hydraulic circuit for a working vehicle is disclosed in International Patent Publication No. WO2006008875, entitled, “Hydraulic Circuit for Working Vehicle.” The WO2006008875 publication describes a hydraulic circuit with a common variable displacement hydraulic pump for supplying pressurized oil to both a working machine actuator and an actuator for driving a cooling fan. In the WO2006008875 publication, the maximum discharge capacity of the variable displacement hydraulic pump is less than the sum of the maximum flow rate required for driving the working machine and the maximum flow rate required for driving the cooling fan. When the flow rate from the hydraulic pump is less than the sum of the maximum flow rate required for driving the working machine and the maximum flow rate required for driving the cooling fan, the control device supplies a flow rate required for driving the working machine and the remaining flow rate to the actuator for driving the cooling fan. While effective, improvements are still desired to provide flow to both the linkages and the cooling fan.

SUMMARY OF THE DISCLOSURE

In accordance with one embodiment, a control system for a machine having a cylinder and an accessory is disclosed. The control system may include a pump configured to provide fluid to the cylinder and the accessory, and a controller operatively connected to the pump. The controller may be configured to operate the pump to provide a primary flow to the cylinder at up to a predetermined maximum level for the cylinder. The predetermined maximum level for the cylinder may be less than a maximum flow capability of the pump. The controller may also be configured to operate the pump to provide a secondary flow to the accessory utilizing a remaining fluid.

In accordance with another embodiment, a machine is disclosed. The machine may include a linkage, a cylinder operatively connected to the linkage, an accessory, a first pump configured to provide fluid flow to move the cylinder and the accessory, an engine coupled to the first pump and configured to drive the first pump, and a controller in operative communication with the first pump and the engine. The controller may be configured to determine an amount of primary flow to the cylinder. the amount of primary flow to the cylinder may be less than a maximum flow capability of the first pump. The controller may also be configured to determine an amount of secondary flow to the accessory. The amount of secondary flow may be less than or equal to the maximum flow capability of the first pump minus the amount of primary flow to the cylinder. The controller may also be configured to calculate a displacement of the first pump to provide the determined amount of primary flow to the cylinder and the determined amount of secondary flow to the accessory, and control the first pump according to the calculated displacement.

In accordance with yet another embodiment, a control system for a machine having a cylinder and an accessory is disclosed. The control system may include an engine and a pump coupled to the engine. The pump may be configured to convert mechanical energy from the engine into fluid flow for the cylinder and the accessory. The control system may also include a controller in operative communication with the engine and the pump. The controller may be configured to determine an amount of primary flow to the cylinder based at least in part on an operator request for the cylinder, determine an amount of secondary flow to the accessory based at least in part on a desired fan speed, calculate a speed of the engine to provide the determined amount of primary flow to the cylinder and the determined amount of secondary flow to the accessory, and operate the engine according to the calculated speed of the engine.

These and other aspects and features will become more readily apparent upon reading the following detailed description when taken in conjunction with the accompanying drawings. In addition, although various features are disclosed in relation to specific exemplary embodiments, it is understood that the various features may be combined with each other, or used alone, with any of the various exemplary embodiments without departing from the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a machine, in accordance with one embodiment of the present disclosure;

FIG. 2 is a diagrammatic view of a control system for the machine of FIG. 1;

FIG. 3 is a flow diagram illustrating an example algorithm to provide a constant net implement pump flow strategy, in accordance with another embodiment;

FIG. 4 is a diagrammatic view of the control system of FIG. 2 illustrating an example flow scenario for a pump;

FIG. 5 is a diagrammatic view of the control system of FIG. 2 illustrating another example flow scenario for the pump of FIG. 4;

FIG. 6 is a diagrammatic view of the control system of FIG. 2 illustrating another example flow scenario for an engine coupled to a pump;

FIG. 7 is a flowchart illustrating an example process for controlling a pump of the machine, in accordance with another embodiment; and

FIG. 8 is a flowchart illustrating an example process for controlling an engine of the machine, in accordance with yet another embodiment.

While the present disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof will be shown and described below in detail. The disclosure is not limited to the specific embodiments disclosed, but instead includes all modifications, alternative constructions, and equivalents thereof.

DETAILED DESCRIPTION

The present disclosure provides a control system for a machine that generates a consistent pump flow to cylinders of the machine regardless of an operation of other flow consuming devices, or accessories. The disclosed control system operates a pump and/or an engine to provide up to a maximum level of flow for the cylinders, which is less than an overall maximum capability of the pump, and operates the accessories utilizing the remaining fluid. The pump may be sized to meet the maximum level of flow for the cylinders plus a maximum level of flow for the accessories. Furthermore, an engine speed may be adjusted based on a load of the accessories in order to provide the requisite fluid output from the pump. In so doing, the disclosed control system meets desired flow requirements for both the cylinders and the accessories without adding extra hardware.

Referring now to the drawings, and with specific reference to FIG. 1, a machine consistent with certain embodiments of the present disclosure is generally referred to by reference numeral 20. Generally, corresponding reference numbers will be used throughout the drawings to refer to the same or corresponding parts. It is to be understood that although the machine 20 is illustrated as a hydraulic excavator, the machine 20 may be of many other types. As used herein, the term “machine” refers to a mobile machine that performs a driven operation involving physical movement associated with a particular industry, such as, earthmoving, construction, landscaping, forestry, transportation, agriculture, mining, etc.

Non-limiting examples of machines include commercial and industrial machines, such as, excavators, loaders, earth-moving vehicles, dozers, motor graders, tractors, backhoes, trucks, mining vehicles, on-highway vehicles, trains, agricultural equipment, material handling equipment, and other types of machines that operate in a work environment. It is to be understood that the machine 20 is shown primarily for illustrative purposes to assist in disclosing features of various embodiments, and that FIG. 1 does not depict all of the components of a machine.

The machine 20 may include traction devices 24, an implement assembly 26, an engine 28 or other power source, and an operator cab 30. Although traction devices 24 are shown as tracks, traction devices 24 may be wheels or of any other type. The implement assembly 26 may include a bucket 32 or other implement mounted to one or more linkages 34. The engine 28 may provide mechanical power to a hydraulic system 36, which is configured to drive and control the traction devices 24 and the implement assembly 26. However, power systems other than the hydraulic system 36 may be used, such as, a mechanical system, an electrical system, a pneumatic system, and the like.

The operator cab 30 may contain an operator interface 38, which may be configured to receive input from and output data to an operator of the machine 20. The operator interface 38 may include a plurality of operator controls for controlling operation of the machine 20 and the implement assembly 26. For example, the operator interface 38 may include one or more joysticks for manipulating the bucket 32 and linkages 34. Other examples of operator controls may include, but not be limited to, one or more levers, dials, pedals, buttons, switches, steering wheels, screens, displays, monitors, touchscreens, keyboards, control panels, instrument panels, gauges, speakers, voice recognition software, microphones, etc.

Referring now to FIG. 2, with continued reference to FIG. 1, the machine 20 may further include a control system 40, in accordance with an embodiment of the present disclosure. The control system 40 may comprise a controller 42 in operative communication with the engine 28 and the hydraulic system 36. The controller 42 may be implemented using one or more of a processor, a microprocessor, a microcontroller, a digital signal processor (DSP), a field-programmable gate array (FGPA), an electronic control module (ECM), an electronic control unit (ECU), and a processor-based device that may include or be associated with a non-transitory computer readable storage medium having stored thereon computer-executable instructions, or any other suitable means for electronically controlling functionality of the engine 28 and the hydraulic system 36.

The controller 42 may be configured to operate according to predetermined algorithms or sets of instructions for operating the engine 28 and the hydraulic system 36. Such algorithms or sets of instructions may be programmed or incorporated into a memory 44 that is associated with or at least accessible to the controller 42. The memory 44 may be provided within and/or external to the controller 42, and may comprise a non-volatile memory. It is understood that the control system 40 and controller 42 may include other hardware, software, firmware, and combinations thereof.

In addition, the control system 40 may comprise more than one controller 42. For example, the controller 42 may be a machine controller associated with the overall machine 20, while another controller 46 may be an engine controller associated with just the engine 28. The controller 46 of the engine 28 may have a memory 48 and may be in communication with the controller 42 of the machine 20. However, other configurations may certainly be used. In an example, the control system 40 may comprise a single controller for both the machine 20 and the engine 28.

As shown in FIG. 2, the hydraulic system 36 may include one or more pumps 50, 52 valves 54, 56, cylinders 58, accessories 60, and the like. Furthermore, signals from the controller 42 may be, for example, electro-hydraulic signals that control operation of the hydraulic system 36 and the engine 28. More specifically, the engine 28 may be coupled to a first pump 50 and a second pump 52. The engine 28 may be configured to drive the first pump 50 and the second pump 52, supplying mechanical power thereto.

Each of the first pump 50 and the second pump 52 may comprise a variable displacement pump, although other types of pumps may be used. The first pump 50 may be configured to convert mechanical energy from the engine 28 into hydraulic energy or fluid flow to move the cylinders 58 and the accessory 60. The second pump 52 may be configured to convert mechanical energy from the engine 28 into additional hydraulic energy or fluid flow to move the cylinders 58. However, other configurations may be used. For example, the hydraulic system 36 may only have one pump instead of two pumps, or the hydraulic system 36 may have more than two pumps.

In addition, the controller 42 may be in communication with the first pump 50 and the second pump 52. More specifically, the controller 42 may control the first pump 50 and the second pump 52 through a proportional solenoid on each of the first pump 50 and the second pump 52. Each proportional solenoid produces a certain displacement on the first pump 50 and the second pump 52, as commanded by the controller 42. Furthermore, each of the first pump 50 and the second pump 52 may have an associated displacement sensor configured to detect an actual pump displacement. The displacement sensors may be connected to the controller 42 in order to provide closed loop electronic control and ensure correct displacement on the first pump 50 and the second pump 52.

The controller 42 may determine an actual flow leaving each of the first pump 50 and the second pump 52 by multiplying a speed of the engine 28 by the pump displacement. The pump displacement of each of the first pump 50 and the second pump 52 may be detected by the displacement sensors, which send signals to the controller indicative of the actual pump displacements of the first pump 50 and the second pump 52. For the speed of the engine 28, the operator may request a desired engine speed through the operator interface 38 in the operator cab 30, such as, through a dial or other type of operator control.

Furthermore, the engine 28 may have one or more associated speed sensors configured to detect an actual speed of the engine. The speed sensors may be connected to the controller 42, and may be configured to send signals to the controller indicative of the actual speed of the engine 28. To determine the actual flow leaving each of the first pump 50 and the second pump 52, the controller 42 may multiply the actual pump displacement of each pump by the actual speed of the engine 28.

A main valve 54 may control flow from the first pump 50 and the second pump 52 to the cylinders 58, while an accessory valve 56 may control flow from the first pump 50 to the accessory 60. The main valve 54 may comprise a hydraulic control valve or other type of valve. The cylinders 58 may comprise hydraulic cylinders that are operatively connected to the linkages 34 and configured to move the linkages 34 based on operator input into a joystick 62 or other type of operator control. It is to be understood that the main valve 54 may control flow to other main hydraulic components than the cylinders 58.

In addition, a pilot source 64 may provide a pressure to the joystick 62. When the operator moves the joystick 62, the pressure from the pilot source 64 is transferred to the main valve 54, thereby moving a spool of the main valve 54 and regulating fluid flow to the cylinders 58. However, the main valve 54 may be actuated in other ways than pilot hydraulics. For example, the main valve 54 may be controlled electro-hydraulically as well.

Moreover, the controller 42 may be in communication with a pressure sensor 66. The pressure sensor 66 may be configured to detect a negative flow control pressure coming from the main valve 54 as the spool of the main valve 54 is moved in response to the operator input into the joystick 62. Thus, the negative flow control pressure provides an indication of an operator request for the cylinders 58. The pressure sensor 66 may send a signal indicative of the negative flow control pressure, or the operator request for the cylinders 58, to the controller 42.

The accessory 60 shown in FIG. 2 may comprise a hydraulically driven cooling fan. However, other flow consuming devices may also be used as accessories 60. The accessory valve 56 may comprise an electronic pressure reducing valve, although other types of valves may be used. The controller 42 may be in communication with the accessory valve 56, and may be configured to send signals to the accessory valve 56 to control pressure of the fluid flow from the first pump 50. In so doing, the controller 42 may control the accessory valve 56 in order to regulate a speed of the cooling fan.

Turning now to FIG. 3, with continued reference to FIGS. 1 and 2, a flow diagram illustrating an example algorithm 70 that may be included in the control system 40 of the machine 20 is shown. For example, the algorithm may be programmed into the memory 44 of the controller 42. When implemented by the controller 42, the algorithm 70 may provide a constant net implement pump flow strategy for the first pump 50. More specifically, the controller 42 may use the algorithm 70 in order to provide a consistent fluid flow from the first pump 50 to the cylinders 58, regardless of the fluid flow consumed from the first pump 50 by the accessory 60.

At module 72, the controller 42 may determine an amount of primary flow 74 to the cylinders 58. Based on the operator request 76 for the cylinders 58, a predetermined minimum flow level 78 for the first pump 50, and a predetermined maximum flow level 80 for the cylinders 58, the controller 42 may determine the amount of primary flow 74 to deliver to the cylinders 58. The operator request 76 for the cylinders 58 may be derived from the negative flow control pressure detected by the pressure sensor 66 along with other logic preprogrammed into the memory 44 of the controller 42.

The predetermined minimum flow level 78 for the first pump 50 may also be preprogrammed into the memory 44 of the controller 42. For example, the predetermined minimum flow level 78 for the first pump 50 may be approximately twenty cubic centimeters (20 cc), depending on physical requirements of the first pump 50 and other components of the hydraulic system 36. However, other numerical amounts for the predetermined minimum flow level 78 may be used.

The predetermined maximum flow level 80 for the cylinders 58 may also be preprogrammed into the memory 44 of the controller 42. The predetermined maximum flow level 80 for the cylinders 58 may depend on the physical requirements of the cylinders 58 and other components of the hydraulic system 36 and machine 20. According to an embodiment of the present disclosure, the predetermined maximum flow level 80 for the cylinders 58 may be less than a maximum flow capability 84 of the first pump 50. More specifically, when designing and implementing the hydraulic system 36 of the machine 20, the first pump 50 may be sized such that its maximum flow capability 84 is greater than the predetermined maximum flow level 80 for the cylinders 58.

In one embodiment, the predetermined maximum flow level 80 for the cylinders 58 may be calculated at module 82. For example, the predetermined maximum flow level 80 for the cylinders 58 may be equal to the maximum flow capability 84 of the first pump 50 minus a predetermined maximum flow level 86 for the accessory 60. The predetermined maximum flow level 86 for the accessory 60 may be preprogrammed into the memory 44 of the controller and may depend on the physical requirements of the accessory 60 and other components of the hydraulic system 36.

Using the predetermined maximum flow level 80 for the cylinders 58 and the predetermined minimum flow level 78 for the first pump 50 as upper and lower bounds, respectively, the controller 42 may ensure the first pump 50 is not over-commanded or under-commanded. More specifically, if the operator request 76 for the cylinders 58 is greater than the predetermined maximum flow level 80 for the cylinders 58, module 72 will output the predetermined maximum flow level 80 for the cylinders 58 as the amount of primary flow 74 for the cylinders 58.

If the operator request 76 for the cylinders 58 is less than the predetermined minimum flow level 78 for the first pump 50, module 72 will output the predetermined minimum flow level 78 for the first pump 50 as the amount of primary flow 74 for the cylinders 58. Otherwise, if the operator request 76 for the cylinders 58 is less than or equal to the predetermined maximum flow level 80 for the cylinders 58 and greater than or equal to the predetermined minimum flow level 78 for the first pump 50, module 72 will output the operator request 76 for the cylinders 58 as the amount of primary flow 74 for the cylinders 58. The controller 42 may determine the amount of primary flow 74 to the cylinders 58 independent from a determination of an amount of secondary flow 90 to the accessory 60.

At module 88, the controller 42 may determine the amount of secondary flow 90 to the accessory 60. For example, based on a fan motor size 92 and a desired fan speed 94, the controller 42 may calculate the amount of secondary flow 90 to deliver to the cooling fan or accessory 60. Preprogrammed into the memory 44 of the controller 42, the fan motor size 92 depends on the physical design and dimensions of a motor used to power the cooling fan or accessory 60.

The desired fan speed 94 may depend on the real-time cooling requirements of the engine 28 and the machine 20 during operation. For example, the controller 42 may determine the desired fan speed 94 based on a hydraulic oil temperature, an ambient temperature, a fuel temperature, and other feedback detected by temperature sensors or other means. Using the various temperatures and current machine conditions, the controller 42 may use a look-up table preprogrammed into the memory 44 of the controller 42 in order to determine the desired fan speed 94 needed to cool the engine 28 and the machine 20.

In order to determine the amount of secondary flow 90 for the accessory 60, the controller 42 may multiply the desired fan speed 94 by the fan motor size 92. At module 96, the controller 42 may determine a final pump flow request 98 based on the determined amount of primary flow 74 for the cylinders 58 and the determined amount of secondary flow 90 for the accessory 60. More specifically, the final pump flow request 98 may be equal to a sum of the determined amount of primary flow 74 for the cylinders 58 and the determined amount of secondary flow 90 for the accessory 60.

The controller 42 may convert the final pump flow request 98 into a desired pump displacement that is commanded to the first pump 50 in order to provide the determined amount of primary flow 74 to the cylinders 58 and the determined amount of secondary flow 90 to the accessory 60. For example, the controller 42 may calculate the desired pump displacement by dividing the final pump flow request 98 by the actual speed of the engine 28 detected by engine speed sensors. The controller 42 may control the first pump 50 and send signals according to the calculated pump displacement. In addition, the controller 42 may control the accessory valve 56 and send signals according to the determined amount of secondary flow 90 for the accessory 60.

The controller 42 may be configured to operate the first pump 50 to provide the primary flow 74 to the cylinders 58 at up to the predetermined maximum flow level 80 for the cylinders 58. To ensure the primary flow 74 to the cylinders 58 is consistent and the operator experiences a consistent joystick to cylinder velocity relationship, the predetermined maximum flow level 80 for the cylinders 58 may be less than the maximum flow capability of the first pump 50. Furthermore, the controller 42 may be configured to operate the first pump 50 to provide the secondary flow 90 to the accessory 60 utilizing the remaining fluid from the first pump 50. The remaining fluid from the first pump 50 may be equal to the maximum flow capability of the first pump 50 minus the amount of primary flow 74 to the cylinders 58.

According to an embodiment of the present disclosure, the first pump 50 may be sized such that the maximum flow capability of the first pump 50 is equal to or greater than the predetermined maximum flow level 80 for the cylinders plus the predetermined maximum flow level 86 for the accessory 60. In an example illustrated in FIGS. 4 and 5, by sizing the first pump 50 with a maximum flow capability equal to a sum of the predetermined maximum flow level 80 for the cylinders 58 and the predetermined maximum flow level 86 for the accessory 60, the controller 42 may command the first pump 50 to accommodate maximum flow requirements for both the cylinders 58 and the accessory 60.

In the example of FIGS. 4 and 5, 100% efficiency or sufficient engine power may be assumed. In addition, a fan motor size may be 50 cubic centimeters per revolution (cc/rev), a minimum fan speed may be 0 revolutions per minute (rpm), a maximum fan speed may be 1000 rpm, and an engine speed may be 2000 rpm. A size of each of the first pump 50 and the second pump 52 may be variable between 20 cc/rev to 175 cc/rev, and a flow request of the cylinders 58 may be at 100% or 600 liters per minute (lpm) in the example. However, other assumptions and numerical dimensions for the example in FIGS. 4 and 5 may be used.

For instance, in FIG. 4, when the desired fan speed is at a minimum, such as, at 0 rpm, the controller 42 may command a displacement of 150 cc/rev to each of the first pump 50 and the second pump 52 in order to provide the predetermined maximum flow level 80 to the cylinders 58 of 600 lpm, for example. As shown in FIG. 5, when the desired fan speed is at a maximum, such as, at 1000 rpm, the controller 42 may command an increased displacement of 175 cc/rev to the first pump 50 in order to provide the predetermined maximum flow level 80 to the cylinders 58 of 600 lpm and the predetermined maximum flow level 86 for the accessory 60 of 50 lpm, for example.

In the example of FIGS. 4 and 5, the maximum flow capability of the first pump 50 is 175 cc/rev. Taken with the maximum flow capability of the second pump 52 of 150 cc/rev, the first pump 50 and the second pump 52 provide an overall maximum flow capability that is equal to the predetermined maximum flow level 80 of the cylinders 58 and the predetermined maximum flow level 86 of the accessory 60. As such, the controller 42 is able to command the increased displacement to provide maximum flow requirements for both the cylinders 58 and the accessory 60 without having to sacrifice flow to the cylinders 58 or the accessory 60.

In addition, the second pump 52 may have a maximum flow capability equal to that of the first pump 50, such as, 175 cc/rev, thereby providing an overall maximum flow capability that is greater than the maximum flow requirements for both the cylinders 58 and the accessory 60. However, the controller 42 may still command a displacement of 150 cc/rev to the second pump 52 since the second pump 52 is providing additional flow to the cylinders 58 only. It is to be understood that the numerical dimensions described and illustrated above in connection with FIGS. 4 and 5 are for example purposes only, and that any range of numerical dimensions may be used with the engine 28, the controller 42 and the hydraulic system 36.

In accordance with another embodiment of the present disclosure, the controller 42 may be configured to adjust the speed of the engine 28 in order to provide the determined amount of primary flow 74 to the cylinders 58 and the determined amount of secondary flow 90 to the accessory 60. Instead of converting the final pump flow request 98 into a desired pump displacement for the first pump 50, the controller 42 may convert the final pump flow request 98 into a desired engine speed that is commanded to the engine 28.

In an example illustrated in FIG. 6, 100% efficiency or sufficient engine power may be assumed. In addition, the fan motor size may be 50 cc/rev, the minimum fan speed may be 0 rpm, and the maximum fan speed may be 1000 rpm. The size of each of the first pump 50 and the second pump 52 may be variable between 20 cc/rev to 150 cc/rev, and a flow request of the cylinders 58 may be at 100% or 600 lpm in the example. However, other assumptions and numerical dimensions for the example in FIG. 6 may be used.

The controller 42 may calculate the desired engine speed by dividing the final pump flow request 98 by the maximum flow capability of the first pump 50. For instance, in the example of FIG. 6, if the final pump flow request 98 for the first pump 50 is 350 lpm, and the maximum flow capability of the first pump is 150 cc/rev, the controller 42 may calculate the desired engine speed to be 2333 rpm. However, the controller 42 may use other techniques to calculate the desired engine speed.

The controller 42 may control the engine 28 and send signals to the controller 46 of the engine 28 according to the calculated engine speed. In so doing, maximum flow requirements for both the cylinders 58 and the accessory 60 may still be met without having to increase the size of the first pump 50. It is to be understood that the numerical dimensions in FIG. 6 are for example purposes only, and that any range of numerical dimensions may be used with the engine 28, the controller 42 and the hydraulic system 36.

INDUSTRIAL APPLICABILITY

In general, the foregoing disclosure finds utility in various industrial applications, such as, in earthmoving, construction, industrial, agricultural, mining, transportation, and forestry machines. In particular, the disclosed control system may be applied to excavators, loaders, earth-moving vehicles, dozers, motor graders, tractors, backhoes, trucks, mining vehicles, on-highway vehicles, trains, agricultural equipment, material handling equipment, and the like.

By applying the disclosed control system to a machine, maximum flow requirements for both the cylinders and the accessory may be met without adding extra hardware to the machine. In particular, the disclosed control system operates a pump and/or an engine to provide up to a maximum level of flow for the cylinders, which is less than an overall maximum capability of the pump, and operates the accessory utilizing the remaining fluid. In so doing, a consistent joystick to cylinder velocity relationship is provided to the operator of the machine regardless of an operation of the accessory.

Turning now to FIG. 7, with continued reference to FIGS. 1-6, a flowchart illustrating an example process 100 for controlling the first pump 50 of the machine 20 is shown, in accordance with another embodiment. The process 100 may be programmed into the memory 44 associated with the controller 42 of the machine 20. At block 102, the controller 42 may determine an amount of primary flow 74 to the cylinder 58. The amount of primary flow 74 to the cylinder 58 may be less than a maximum flow capability of the first pump 50.

At block 104, the controller 42 may determine an amount of secondary flow 90 to the accessory 60. The amount of secondary flow 90 may be less than or equal to the maximum flow capability of the first pump 50 minus the amount of primary flow 74 to the cylinder 58. The controller 42 may calculate a displacement of the first pump 50 to provide the determined amount of primary flow 74 to the cylinder 58 and the determined amount of secondary flow 90 to the accessory 60, at block 106. At block 108, the controller 42 may control the first pump 50 according to the calculated displacement.

Referring now to FIG. 8, with continued reference to FIGS. 1-7, a flowchart illustrating an example process 110 for controlling the engine 28 of the machine 20 is shown, in accordance with another embodiment. The process 110 may be programmed into the memory 44 associated with the controller 42 of the machine 20. At block 112, the controller 42 may determine an amount of primary flow 74 to the cylinder 58 based at least in part on an operator request for the cylinder 58.

At block 114, the controller 42 may determine an amount of secondary flow 90 to the accessory 60 based at least in part on a desired fan speed. The controller 42 may calculate a speed of the engine 28 to provide the determined amount of primary flow 74 to the cylinder and the determined amount of secondary flow 90 to the accessory 60, at block 116. At block 118, the controller 42 may operate the engine 28 according to the calculated speed of the engine 28.

It is to be understood that the flowcharts in FIGS. 7 and 8 are shown and described as examples only to assist in disclosing the features of the disclosed system, and that more or less steps than that shown may be included in the processes corresponding to the various features described above for the disclosed system without departing from the scope of the disclosure.

While the foregoing detailed description has been given and provided with respect to certain specific embodiments, it is to be understood that the scope of the disclosure should not be limited to such embodiments, but that the same are provided simply for enablement and best mode purposes. The breadth and spirit of the present disclosure is broader than the embodiments specifically disclosed and encompassed within the claims appended hereto. Moreover, while some features are described in conjunction with certain specific embodiments, these features are not limited to use with only the embodiment with which they are described, but instead may be used together with or separate from, other features disclosed in conjunction with alternate embodiments. 

1. A control system for a machine having a cylinder and an accessory, the control system comprising: a pump configured to provide fluid to the cylinder and the accessory; and a controller operatively connected to the pump, the controller configured to: operate the pump to provide a primary flow to the cylinder at up to a predetermined maximum level for the cylinder, the predetermined maximum level for the cylinder being less than a maximum flow capability of the pump, the maximum flow capability of the pump being equal to or greater than the predetermined maximum level for the cylinder plus a predetermined maximum level for the accessory, and operate the pump to provide a secondary flow to the accessory utilizing a remaining portion of the fluid, the secondary flow being provided to the accessory at up to the predetermined maximum level for the accessory.
 2. (canceled)
 3. The control system of claim 1, wherein the control system further comprises an engine coupled to the pump, wherein the engine is configured to drive the pump, and wherein the controller is in operative communication with the engine and is further configured to adjust a speed of the engine such that the pump provides the primary flow to the cylinder and the secondary flow to the accessory.
 4. The control system of claim 1, wherein the accessory is a cooling fan.
 5. The control system of claim 1, further comprising a second pump configured to provide additional flow to the cylinder.
 6. The control system of claim 1, wherein the controller is further configured to receive a signal indicative of an operator request for the cylinder.
 7. The control system of claim 6, wherein the controller is further configured to calculate a pump displacement based at least in part on the operator request for the cylinder.
 8. The control system of claim 7, wherein the controller is further configured to calculate the pump displacement based at least in part on a desired fan speed.
 9. The control system of claim 8, wherein the controller is further configured to calculate the pump displacement based at least in part on an engine speed.
 10. The control system of claim 9, wherein the controller is further configured to control the pump according to the calculated pump displacement in order to provide the primary flow to the cylinder and the secondary flow to the accessory.
 11. A machine, comprising: a linkage; a cylinder operatively connected to the linkage; an accessory; a first pump configured to provide fluid flow to move the cylinder and the accessory; an engine coupled to the first pump and configured to drive the first pump; and a controller in operative communication with the first pump and the engine, the controller configured to: determine an amount of primary flow to the cylinder, the amount of primary flow to the cylinder being less than a maximum flow capability of the first pump, the maximum flow capability of the first pump being equal to or greater than a sum of a predetermined maximum level for the cylinder and a predetermined maximum level for the accessory, determine an amount of secondary flow to the accessory, the amount of secondary flow being less than or equal to the maximum flow capability of the first pump minus the determined amount of primary flow to the cylinder, calculate a displacement of the first pump to provide the determined amount of primary flow to the cylinder at up to the predetermined maximum level for the cylinder and provide the determined amount of secondary flow to the accessory at up to the predetermined maximum level for the accessory, and control the first pump according to the calculated displacement.
 12. (canceled)
 13. The machine of claim 11, wherein the controller is further configured to adjust a speed of the engine such that the first pump provides the determined amount of primary flow to the cylinder and the determined amount of secondary flow to the accessory.
 14. The machine of claim 11, wherein the machine is a hydraulic excavator.
 15. The machine of claim 11, wherein the controller is further configured to determine the amount of primary flow to the cylinder independent of the amount of secondary flow to the accessory.
 16. The machine of claim 11, wherein the accessory is a cooling fan.
 17. The machine of claim 16, wherein the controller is further configured to calculate the displacement of the first pump based on an operator request for the cylinder, a desired fan speed, and a speed of the engine.
 18. The machine of claim 11, further comprising a second pump configured to provide fluid flow to the cylinder, wherein the controller is in operative communication with the second pump, and wherein the controller is further configured to: calculate a displacement of the second pump to provide an additional flow to the cylinder, and control the second pump according to the calculated displacement.
 19. The machine of claim 18, wherein the calculated displacement of the first pump is greater than the calculated displacement of the second pump.
 20. A control system for a machine having a cylinder and an accessory, the control system comprising: an engine; a pump coupled to the engine, the pump configured to convert mechanical energy from the engine into fluid flow for the cylinder and the accessory; and a controller in operative communication with the engine and the pump, the controller configured to: determine an amount of primary flow to the cylinder based at least in part on an operator request for the cylinder, determine an amount of secondary flow to the accessory based at least in part on a desired fan speed, calculate a speed of the engine to provide the determined amount of primary flow to the cylinder and the determined amount of secondary flow to the accessory, and operate the engine according to the calculated speed of the engine.
 21. The control system of claim 20, further comprising an additional pump configured to provide additional flow to the cylinder.
 22. The control system of claim 20, wherein the controller is configured to calculate the speed of the engine based on the determined amount of primary flow to the cylinder, the determined amount of secondary flow to the accessory, and a maximum flow capability of the pump. 